Fused projector lamp



Dec. 17, 1968 R. E. SMITH ET AL FUSED PROJECTOR LAMP Filed April 28, 1966 FEGJ L W E S IWK 00 N WOE T HH m D 1 R 5 A L H R RCC United States Patent 3,417,286 FUSED PROJECTOR LAMP Richard E. Smith and Conrad D. Holmes, Lexington, and Charles E. Henltel, Winchester, Ky asslgnors to Sylvania Electric Products Inc., a corporation of Delaware Filed Apr. 2a, 1966 Ser. No. 546,035 6 Claims. cl. 315-74) ABSTRACT OF THE DISCLOSURE A fused projector lamp in which the fuse wire is provided with a sleeve of fiber glass tubing which encircles it and both are curved to lengthen the arc and lessen the violence of arcing by channeling the arc in a direction of lesser field intensity.

This invention relates to the manufacture of electric lamps and more particularly to projector lamps having an internal fuse.

Generally speaking it has been the practice heretofore to obtain internal fusing of projector lamps by threading a fuse wire through a length of glass tubing. open at both ends, so that the glass tubing acts as a sleeve through which the fuse wire extends. This arrangement has proven to be reasonably satisfactory with low volt or line volt lamps. With these types of lamps, the arcing which occurs when the fuse operates is not particularly violent and usually no damage is caused to the sleeve of glass tubing or to other lamp components, such as the intemai reflector or the lamp envelope for example. However, this type of fuse arrangement with high volt lamps leaves much to be desired.

When used with 220-240 volt projector lamps, the use of a length of glass tubing as the sleeve through which a fuse wire extends is not satisfactory. With these high voltage lamps, the sleeve of glass tubing acts like a shotgun barrel spewing forth hot metal particles from each of the open ends of the glass tubing when the fuse wire performs its primary purpose of breaking the circuit. These hot metal particles sometimes strike the wall of the lamp envelope and shatter it. in other cases, particularly where the reflector is located in close proximity to the fuse, the fuse operates so violently that arcing over to the reflector also occurs. Thus this restablished are can result in blowing a line fuse of a very high ampere capacity.

In view of the foregoing, one of the principal objects of this invention is to provide a satisfactory fusing arrangement for high volt projector lamps.

This and other objects, advantages and features are attained, in accordance with the principles of this invention, by providing the fuse wire with a sleeve of fiber glass tubing. In .the preferred embodiment of the invention illustrated in the accompanying drawing and described below, the fuse wire and the sleeve of fiber glass tubing which encircles it are curved to lengthen the arc and lessen the violence of arcing by channeling the arc in a direction of lesser field intensity. The size of the fiber glass tubing is selected to provide sufficient mass to resist melting. The size of the fuse wire is selected to minimize metal Vapor.

In the specific embodiment of the invention illustrated in the accompanying drawing, FIGURE l is a front elevationai view of a projector lamp having the fuse arrangement of this invention.

FIGURE 2 is a side elevational view of the lamp of FIG. 1.

pins.

3,417,286 Patented Dec. 17, 1968 FIGURE 3 is an enlarged fragmentary detail of the fuse arrangement of FIGS. 1 and 2.

FIGURE 4 is an enlarged fragmentary detail of one of dthze weld junctions of the fuse arrangement of FIGS. 1 an Referring now to the drawing, particularly FIGS. l and 2 thereof, the projector lamp illustrated therein comprises an hermetically sealed, substantially tubular glass envelope 1 having a coating 3 of an enamel glaze at one end and a metal base 5 at the other end. A lamp orienting post 7 and lead-in pins 9, 10, 11 and 12 depend from the bottom of the base 5. Lead-in pins 9, I0, 11 and 12 extend into the inside of the lamp envelope 1 and support the mount structure therein. The mount structure comprises a multisegment filament 15, the ends of which are threaded over inserts 17 welded to side rods 19. Each segment of the filament has a loop at each end thereof, said loops providing the means whereby the filament segments are hung on upper filament support hooks 2i and stretched over lower filament support hooks 23. The hooks 2i depend from a glass rod or bridge which is in turn mounted on spuds 27 welded to the side rods 19. The hooks 23 are upstanding on a glass rod or bridge 29 which is in turn supported by brackets 31 welded to side rods 19. The side rods 19 are welded to the inner ends or lead=in pins -9: and AIL-A brace 33 connects one of the side rods 19 to dummy pin 11 to aid in stabilizing the mount structure.

As shown particularly in H0. 3, a fuse wire 35 of .006" Ni is welded at one end to pin 12 and at the other end to pin 10. The fuse wire 35 is disposed within a sleeve of fiber glass tubing 37, size No. 14 for example, to provide sufficient mass to resist melting. For best results, as shown in FIG. 3, the .pin 12 is shortened in order to lengthen the arc gap and this end of the sleeve 37 overlies the pin 12 for a substantial distance. The other end of the fuse wire 35 is welded to pin 10 at junction of pin 10 and side rod 19. This weld junction acts as a shield for hot metal particles and vapor upon operation of the fuse. This end of the sleeve 37 of fiber glass tubing is preferably drawn well over the weld juncture as shown particularly in FIG. 4.

While there has been shown and described what is at present considered the preferred embodiment of the in vention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention as defined by the appended claims.

What we claim is:

I. An electric lamp comprising: an hermetically sealed, light-transmitting envelope; a mount structure, including a filament, disposed in said envelope; a fuse wire eleetrically connected to said mounted structure, said fuse wire being curved; and a sleeve of fiber glass tubing encircling said curved fuse wire.

2. The combination of claim 1 and a plurality of leadin pins sealed in and extending through said envelope, the extension of one of said pins inside said envelope being shorter than the others and said fuse wire being connected between said shorter pin and one of said longer 3. The combination of claim 2 in which said sleeve overlies said shorter pin for a substantial distance.

4. The combination of claim 1 and a plurality of leadin pins sealed in and extending through said envelope, the extension of one of said pins inside said envelope being shorter than the others, and said. mount strilcture including a pair of side rods mounted on a pair of said leadin pins, said fuse wire being connected between said shorter pin and one of said longer pins..to which one of said side rods is connected.

5. The combination of claim 4 in which said sleeve of fiber glass tubing is drawn'over junction of fuse wire with side rod and lead-in pin. 1

6. The combination of claim 4 in which one end of i said sleeve of fiber glass tubing overlies said shorter'pin References Cited UNITED STATES PATENTS 740,077 9/1903 Bartlett 313414 x 2,727,961 12/1955 Smith 200 131 2,832,868 4/1958 Kozacka 200-131 2,859,381 11/1958 Gray et a1. 315-44 7 JOHN W. HUCKERT, Primary Examiner 10 A. JJAMES, Assistant Examiner. 

